Nanofibers and articles that contain and/or are made from nanofibers have recently attracted interest for use in a variety of consumer product fields. For example, in the field of personal care products such as diapers, tampons, and incontinence pads include therein one or more fibrous mats that are designed to absorb one or more liquids (e.g., blood, urine, etc.). It is known in the art to form such fibrous mats from fibers and/or nanofibers.
A variety of methods known in the art can be used to produce nanofibers suitable for use in non-woven fibrous mats. Such techniques include melt-blowing, nanofibers-by-gas-jet (NGJ), and electrospinning. In a melt-blowing process, a stream of molten polymer or other fiber-forming material is typically extruded into a jet of gas to form fibers. The resulting fibers are typically greater than 1,000 nanometers in diameter, and more typically, greater than 10,000 nanometers in diameter.
The electrospinning of liquids and/or solutions capable of forming fibers, also known within the fiber forming industry as electrostatic spinning, is well known and has been described in a number of patents as well as in the general literature. The process of electrospinning generally involves the creation of an electrical field at the surface of a liquid. The resulting electrical forces create a jet of liquid that carries an electrical charge. Thus, the liquid jets may be attracted to other electrically charged objects at a suitable electrical potential. As the jet of liquid elongates and travels, the fiber-forming material within the liquid jet will dry and harden. The hardening and drying of the elongated jet of liquid may be caused by cooling of the liquid (i.e., where the liquid is normally a solid at room temperature), evaporation of a solvent (e.g., by dehydration), physically induced hardening, or by a curing mechanism (i.e., chemically induced hardening). The resulting charged fibers are collected on a suitably located, oppositely charged receiver and subsequently removed from it as needed, or directly applied to an oppositely charged or grounded generalized target area. Such fibers can be formed in non-woven fibrous mats, webs or other structures and incorporated, as desired, into a wide range of products.
In some applications, especially those related to personal care products such as diapers, tampons and/or incontinence pads, it is highly desirable to design fibrous mats, webs and/or structures that absorb one or more liquids rapidly, are comfortable to the wearer and are hypoallergenic.
Thus, there is a need in the art for fibrous mats, webs and/or other structures that possess, among other things, improved water absorbing properties and can be used in applications where one or more liquids need to be absorbed rapidly.